Comparison of wind wave properties in Neva Bay and Curonian Lagoon based on modeled data

Abstract

Properties of wind generated waves were studied in the Neva Bay and Curonian Lagoon of the Baltic Sea under typical and extreme meteorological conditions. The coasts of these enclosed shallow (average depth ~3.8 m) water areas of different shape (Curonian lagoon 90×15 (in average) km, Neva Bay 25×10 km) which have a great developing potential (a number of big ports in Neva Bay and the Klaipeda port and UNESCO national natural reserve on the Curonian Spit) are continuously affected by erosion processes. Wave properties were obtained by means of the SWAN model. The calculations were performed based on the wind measurements recorded at the marine and onshore observation sites and recent hydrographic survey. Results show that the significant wave height in both water areas under typical mild winds (7 m/s) doesn't reach 0.5 m and has similar patterns. Moderate winds (11 m/s) develop waves up to 0.7-0.9 m herewith a distinct fetch dependence takes place in the Curonian Lagoon as well as in the Neva Bay. It should be mentioned that the maximum values of wave height in Curonian lagoon are greater by 20 cm. Stormy winds (>19 m/s) produce waves up to 1.2 in Neva Bay and approximately 1.5 m in Curonian lagoon. Most of the storms come from W-SW directions and as usually accompanied by substantial surge (in extreme cases >2 m in Neva Bay and >1.5 m in Curonian lagoon). Sea level rise increases the wave height by a 0.5-1 m in both regions. During severe storms (>26 m/s) the largest developed waves in Neva Bay exceed 2 m with a relatively short period (3-4 s). Under similar meteorological conditions wind waves in Curonian lagoon may reach 2.5 m. In general, impact caused by surge affects the spatial distribution of the highest waves allowing their propagation in the surf and coastal zone. Despite on similarity of the wave properties in both basins for moderate winds a clear difference is observed for storms which can be explained by the greater basin size and bigger area of deep water.